1. Field
This disclosure relates to scalable video compression, more particularly to methods and apparatus for performing scalable video compression with motion compensation in the wavelet domain.
2. Background
Data compression allows less storage space or transmission bandwidth to be used than would be required without compression. Images typically require large amounts of storage space or high amounts of bandwidth for high-quality reproductions. Compression of images, both still and video, seeks to allow high-quality reproductions using the highest amount of compression possible. Compression techniques try to maintain high levels of coding efficiency.
Many standards use block-based image coding techniques. These techniques generally divide an image or a video frame within a sequence into a set of contiguous blocks of pixels. These techniques have several problems, including block-based artifacts that can surface in the reconstructed image. Also, they do not work well in scalable bit streams.
Scalable bit streams occur in heterogeneous systems. A heterogeneous system has links with varying bandwidth, such as a phone connection of 56 K bits per second (bps), an Ethernet connection of 10 Mbps, and a 1.5 Mbps T1 connection. These systems require bit streams that can be scaled to match the bandwidth of the link for the highest quality reproduction of the video sequences at the receiver on this links.
Wavelet compression techniques have found tremendous success in scalable coding of still images, but do not work well for video images because of difficulties with motion compensation and prediction between frames in the video frame sequence. Therefore, a method that allows the scalability of wavelet compression to be used on video images with accurate motion compensation will be useful.